Unitary percussion hand drill



Aug. 25, 1964 H. J. DE BRUlN UNITARY PERCUSSION HAND DRILL Original Filed Sept. 25, 1957 INVENTOR. #060 J 058,910, BY W United States Patent )fiice 3345,2782 Patented Aug. 25, 1964 3,145,782 UNTTARY PERCUSSION HAND DRILL Hugo J. De Bruin, Esmond, Ill., assignor to Samuel J. Forbes, Cleveland, Ohio Continuation of application Ser. No. 685,487, Sept. 23, 1957. This application Aug. 3, 1962, Ser. No. 214,654 9 Claims. (Cl. 173-48) This invention is in the field of drilling devices and is in the nature of a device for rotating a drill bit against a surface to be drilled, such as a masonry wall or the like, and at the same time to apply cyclical percussion blows to the bit to greatly increase the drilling efficiency. The invention is specifically concerned with an integral unit of a suitable power source, such as a standard electric drill, and what has heretofore been considered an attachment which includes an arrangement for applying cyclical percussion blows.

A primary object of the invention is an attachment for applying percussion blows during drilling so that the rate or frequency of the cyclical blows may be varied.

Another object is a drill mechanism having a percussion blow applying means constructed for adjustment of the impact.

Another object is a drilling device with means for selectively applying percussion blows to the drill bit at the same time during each revolution of the bit, for applying the blows to the bit at different times from one bit revolution to another, or for eliminating the blows altogether.

Another object is a percussion blow type drilling assembly which only requires the operator to use one hand.

Another object is an integral electric drill and percussion assembly which provides percussion blows on the drill bit without axial movement of the bit.

Another object is a clutch arrangement for a percussion drilling assembly so that the rapidity of the blows may be varied.

Another object is a percussion drilling assembly that is far more efficient in its drilling operation because the percussion blows are variably timed and do not occur when the drill bit is in its same rotative position from one revolution to another.

Another object is a percussion drilling arrangement in which various adjustments are provided, all of which closely hug the housing so that the unit may be used in tight or close areas or locations.

Other objects will appear from time to time in the ensuing specification and drawings in which FIG. 1 is a side view, partly in section of my percussion drilling assembly;

FIG. 2 is a section taken along the line 2-2 of FIG. 1; and

FIG. 3 is a detail of the impact adjusting assembly.

In FIG. 1 the unitary percussion drilling assembly has been indicated generally at and includes a suitable electric hand drill 12 which may have a cord connection 14 leading to a suitable source of electric power. It will be understood that the housing contains a suitable electric motor and a switch control by a trigger arrangement 16, but it might be otherwise.

A gear housing 18 is mounted on the forward end of the electric drill and the electric motor (not shown), is constructed to operate a drive shaft 20. The forward end of the drive shaft is mounted in a suitable bearing 22, shown as a ball bearing, but it might be otherwise. The bearing is carried in a suitable socket or seat 24 in the gear housing and the forward end of the gear housing is formed into a suitable somewhat enlarged sockettype flange 26.

A percussion assembly is indicated generally at 28 and includes an outer barrel or housing 30 which may be screw threaded at its rear end as at 32 into the socket 26 on the gear housing. The threading may be such that the rear edge 34 is jammed against a part of the gear housing, but it might be otherwise. One or more suitable locking screws or the like 36 may be used to hold the barrel or housing in place, rigidly connecting it to the gear housing and preventing rotation.

A shaft 38 is rotatably mounted in the housing or barrel and has an enlarged rear socket 40 at its rear end which is screw threaded to a projecting part or end 42 of the main shaft from the electric drill. The rear edge of the enlarged socket 40 On the shaft 38 may abut the inner race of the bearing 22, if desired. But in any event, the enlargement 40 provides a shoulder 44 on the shaft.

A ring 46 is freely mounted in the housing or barrel and abuts the shoulder 44 on the shaft. Opposite the ring the housing is provided with a plurality of openings 48, one being shown in detail in FIG. 3. Each such opening is disposed diagonally generally along a line 50 which is at a predetermined angle A to the axis 52 of the assembly. The rear edge of each of the openings 48 is provided with a plurality of steps or seats 54, in the nature of sockets. A sleeve or ring 56 is mounted around the outside of the housing or barrel. A plurality of pins or screws 58 are connected in this ring and project through the openings or slots 48 into the inner ring 46. One such screw is provided for each slot and I prefer that three pins and three slots or openings be used to provide a stable mounting, although it might be otherwise. In any event, the screws tie the outer ring 56 to the inner ring 46 and the operation will be explained hereinafter.

A suitable bearing 60, preferably a needle hearing but it might be otherwise, is provided around the shaft 38 in engagement with the ring 46 and a washer 62 or the like may be positioned between the bearing and a coil spring 64. A cam or hammer element 66 is positioned in the housing and is mounted freely on the shaft 38. The hammer element has a socket 68 into which the spring extends and with an abutment or shoulder 70 against which the spring seats.

A suitable chuck 72 projects from the forward end of the housing and is connected to the shaft 38 by a pin 74 and longitudinal slot 76 in the shaft. It should be noted that the slot 76 is somewhat elongated axially so that the hereinafter described percussion blows, as applied to the chuck, will not be transmitted through the shaft 38 to the electric motor in the drill. This so called floating chuck feature is disclosed and claimed in my copending application Serial No. 672,205, filed July 16, 1957, and now abandoned.

A sleeve 78 is mounted inside of the housing or barrel and is provided with a suitable key 80 which projects into a longitudinally disposed keyway 82 in the hammer element 66. This prevents rotation of the hammer element but allows it to reciprocate longitudinally. The outer housing or barrel has a shoulder 84 which opposes the rear edge of the sleeve and, at the forward end of the housing, an overhanging or shoulder 86 is provided so that the sleeve is held in position.

The forward end of the outer housing or barrel may be provided with a plurality of longitudinally disposed slots or splits 88 each of which may terminate in a hole or enlargement to prevent stress concentration. These slots or splits allow the forward end of the outer housing to be opened up or contracted for reasons set forth hereinafter.

A portion 92 at the forward end of the outer housing is threaded and the forward corner or area is tapered as at 94. A clamping ring 96 having an internally threaded correspondingly tapered surface may be screwed onto the threaded surface 92 to provide a collet type action. A snap ring 98 or the like may be used to hold the clamping ring 96 in place. Rotation of the clamping ring 96 in the 3 direction that causes rearward movement of the ring will force the forward portions of the outer housing inwardly to clamp the forward part of the sleeve 78. Correspondingly, if the ring is rotated so that it moves in a forward direction, the forward portions of the housing will be allowed to expand thereby freeing the sleeve 78.

I provide a rear annular bearing surface as at 100 inside the housing and a corresponding forward bearing surface 102 which function as forward and rear bearings for the sleeve and may be the only surfaces in contact with it. Thus, only these surfaces must be machined and the rest of the inner surface of the housing may be rough. I may provide suitable holes or openings 104 and 106 in the outer housing and sleeve, respectively, so that the pin 74 may be suitably inserted to connect the chuck and shaft together. To align the lateral holes 108 and 76 in the chuck and shaft with the holes 104 and 106 in the sleeve and housing requires that the chuck be pushed rearwardly compressing the spring 64. When the holes are lined up the pin may merely be dropped or inserted and when the chuck is released the spring 64 will force the shaft, chuck and pin to a forward position out of line with the holes 104 and 106.

Suitable cam surfaces 110 are provided on the forward face of the hammer element and the rear face of the chuck so that upon rotation of the chuck, the hammer will be forced rearwardly compressing the spring. The cam surfaces may have one, two or any suitable number of longitudinally disposed drop-off shoulders to cause the percussion blows. This is shown in detail in my prior copending application Serial No. 672,207, filed July 16, 1957.

The use, operation and function of my invention are as follows:

I have invented a unitary percussion drilling assembly which may be operated by one hand. The operator may use the other hand for any purpose he desires.

The collet mechanism at the forward end of the outer housing or barrel is constructed to adjust the cyclical percussion blows of the hammer elements to the desired frequency. For example, if the ring is rotated rearwardly until the outer housing or barrel tightly grips the sleeve preventing it from rotating, the percussion blows from the hammer element 66 will occur at the same point or at the same time during each revolution of the shaft and chuck. Thus the flutes on the forward end of the drill bits will receive the percussion blows when they are in the same position during each revolution.

When the operator wishes to vary the timing of the percussion blows so that they do not occur when the flutes of the drill bit are in the same position, he merely backs the ring 96 off a little so that slippage occurs between the outer housing or barrel and the inner sleeve. The frictional drag of the collet will be such that while the sleeve rotates, it does not rotate as fast as the chuck and shaft. Accordingly, the timing of the percussion blows will vary from one revolution to another, and I have found that this greatly increases the effectiveness of the drilling operation.

On the other hand, if percussion blows are not desired and only a straight drilling operation is to be carried out, the ring 96 may be backed off completely whereby the sleeve 76 is free to turn freely within the housing or barrel and the hammer element 66 will rotate in unison with the chuck and shaft.

The important point is that the unit is constructed for a straight drilling operation without percussion blows at one extreme and for a drilling operation with cyclically occurring percussion blows at a predetermined rate at the other extreme. By the simple adjustment shown the rate of the percussion blows may be varied between these extremes.

The spring tension causing the percussion blows may be varied by manually pushing the adjustment ring 56 forward and rotating it so that the screws or pins 58 fall in a different one of the shoulders or notches 54. When the screws are firmly seated in any one of the notches, they will stay there even when the blows are being rapidly effected. I have only shown three adjustment positions for the spring tensioning device, but it should be understood that more or less may be used. I find it convenient to provide forward and rear inner bearing surfaces in the housing or barrel 30, such as designated at and 102.

Another important aspect of the invention is that when the device is in use, the operator may rotate the ring 96 to either increase or decrease the rate of the percussion blows. If the operator finds that the drilling operation is moving more slowly than is desired, he may rotate the ring with his free hand until the desired elficiency is acquired. This can be carried out purely by feel or touch during operation. The operator does not have to stop the unit, pull the bit out of the hole, and by trial and error continually adjust the mechanism until the desired frequency of percussion blows is acquired. The entire procedure can be carried out during operation.

If for any reason the operator does not want percussion blows to be applied, but wishes to merely carry out a straight drilling operation, the adjustment 96 may he bracked off until the sleeve 73 is completely free. The spring 64 will have sufficient tension so that the hammer 66 and chuck 72 will be tied together and will rotate in unison. Through the key and slot arrangement the sleeve will also be rotated and the percussion blows will not occur.

The overhang or shoulder 86 at the forward end of the outer housing or barrel is of advantage in that it holds the sleeve in, but at the same time the longitudinal slots 88 allow the forward end of the housing to be opened so that the sleeve may be withdrawn or inserted during initial assembly. To prevent the sleeve from binding in the housing, I provide a slight spacing as at 112 between the shoulder 84 and the rear edge of the sleeve. This is to say that the distance between the forward shoulder 86 and the rear shoulder 84 on the outer housing is slightly greater than the full length of the inner sleeve.

I therefore provide a precussion drilling assembly which may be used to drill and simultaneously apply percussion blows to a drill bit at a predetermined rate or frequency or to merely drill without percussion blows. On the other hand the unit may be adjusted through the clutch connection so that the blows may be applied at any frequency up to the maximum. The spring pressure of the blows may be varied, depending upon the work.

The unit has the advantage that both adjustments are in the form of closely fitted rings spaced along the barrel or outer housing and do not stick out a substantial distance. Thus, the unit may be inserted in tight places or crowded areas without obstruction or interference. Additionally, the adjustment rings do not mar the aesthetic appearance of the unit.

While I have shown and described the preferred form and suggested several modifications of my invention, it should be understood that numerous additional modifications, changes, substitutions and alterations may be made without departing from the inventions fundamental theme. For example, while the bearing 60 is desirable, it is not essential. I refer to the outer ring 56 as being connected to the inner ring 46 by pins or screws, but it might be otherwise. The same is true of the screws 36. With these and other modifications in mind, I wish that my invention be unrestricted except as by the appended claims.

This application is a continuation of my copending application Serial No. 685,487, filed September 23, 1957, now abandoned, for Unitary Percussion Hand Drill.

What is claimed is:

1. In a drilling assembly, a housing, a power source in the housing a shaft rotatably mounted in the housing and connected at one end to the power source, a chuck for releasably receiving a drill bit connected to the other end of the shaft, said shaft constructed so said one end and other end rotate at the same speed, means for cyclically applying percussion blows to the chuck at a predetermined rate, and manually operable means independent of the power source for varying the rate of the percussion blows from the predetermined rate to a different blow-applying rate.

2. The structure of claim 1 wherein said means for cyclically applying percussion blows includes a sleeve within the housing around the shaft, a hammer within the sleeve around the shaft and opposite the chuck, means compelling rotation of said hammer with said sleeve and permitting relative longitudinal movement between them, a spring biasing the hammer toward the chuck, cam surfaces between the hammer and chuck constructed upon rotation of the chuck to force the hammer rearwardly against and compressing the spring and to release the hammer, and wherein said manually operable means includes means for selectively preventing or allowing rotation of the hammer relative to the housing.

3. In a drilling assembly, a housing, a power source in the housing, a shaft rotatably mounted in the housing and connected at one end to the power source, a chuck for releasably receiving a drill bit at the other end of the shaft, means for cyclically applying percussion blows to the chuck at a predetermined rate, and manually operable means for varying the rate of the percussion blows, including a sleeve within the housing around the shaft, said percussion blow-applying meansincluding a hammer within the sleeve around the shaft and opposite the chuck, a spring biasing the hammer toward the chuck, cam surfaces between the hammer and chuck constructed upon rotation of the chuck to force the hammer rearwardly against and compress the spring and to release the hammer, manually operable means for selectively preventing or allowing rotation of the hammer relative to the housing, and manually operable means for adjusting the compression of the spring to vary the intensity of the percussion blows.

4. In a drilling assembly, a housing, a shaft rotatably mounted in the housing, a chuck on the shaft at one end of the housing, means for applying percussion blows to the chuck including a hammer freely mounted on the shaft, a spring for biasing the hammer against the chuck, a sleeve between the housing and hammer, means between the hammer and sleeve permitting axial movement of the hammer but preventing rotation relative to the sleeve, cam surfaces between the chuck and hammer to effect reciprocation of the hammer upon rotation of the chuck, and a collet operatively connecting the housing and sleeve effective to grip the sleeve preventing its rotation, to allow the sleeve to slip within the housing, or to allow the sleeve to rotate freely Within the housing.

5. The structure of claim 4 further characterized in that the collet includes a plurality of longitudinal slots at the said one end of the housing, a threaded exterior tapered cam surface at the said one end of the housing, and a camming ring having a corresponding threaded interior tapered cam surface in mesh with the housings cam surface and effective, upon rotation thereof, to force the sections of the housing between the longitudinal slots inwardly in complete or partial gripping relation with the sleeve.

6. The structure of claim 5 further characterized by and including manually operable means for varying the tension in the spring so that the impact of the hammer on the chuck may be varied.

7. The structure of claim 6 wherein said manually operable means includes a seat ring in the housing mounted freely on the shaft and functioning as a seat for the rear end of the spring, an adjustment ring on the outside of the housing, a plurality of openings in the housing, each having a diagonally disposed, stepped rear edge, and a pin passing through each of the openings connected to the seat and adjustment rings and constructed to engage and be held by a selected one of the steps in the rear edge of the opening.

8. In a drilling assembly, a housing, a power source in the housing, a power shaft mounted in the housing for rotation by the power source, a chuck at the forward end of the shaft constructed to releasably hold drill bits, means for cyclically applying percussion blows to the chuck at a predetermined frequency including a sleeve within said housing and a hammer within said sleeve and a key between said sleeve and hammer permitting relative axial movement but preventing relative rotation between them, said sleeve frictionally engaging said housing and providing a slip clutch for varying the relative rotation between them to vary the frequency of the blows, and manually operable means for operating the slip clutch.

9. In a drilling assembly, a housing, a power source in the housing, an integral shaft rotatably mounted in the housing and connected at one end to the power source, a chuck for releasably receiving a drill bit at the other end of the shaft, a first means surrounding said shaft and including a member attached to said shaft, a second means longitudinally movable to said shaft actuated by said first means for cyclically applying percussion blows to the chuck at a predetermined rate and intensity, and manually operable means adapted to engage said second means for varying the rate of the percussion blows to a plurality of different rates.

References Cited in the file of this patent UNITED STATES PATENTS 914,215 Adams Mar. 2, 1909 1,118,692 Sone Nov. 24, 1914 1,190,657 Kollack et a1. July 11, 1916 1,656,054 Gage Jan. 10, 1928 2,223,727 Homen Dec. 3, 1940 2,457,565 Kott Dec. 28, 1948 2,518,429 Moorehead Aug. 8, 1950 2,780,106 Lovequist Feb. 5, 1957 2,794,621 Beeson June 4, 1957 

1. IN A DRILLING ASSEMBLY, A HOUSING, A POWER SOURCE IN THE HOUSING A SHAFT ROTATABLY MOUNTED IN THE HOUSING AND CONNECTED AT ONE END TO THE POWER SOURCE, A CHUCK FOR RELEASABLY RECEIVING A DRILL BIT CONNECTED TO THE OTHER END OF THE SHAFT, SAID SHAFT CONSTRUCTED SO SAID ONE END AND OTHER END ROTATE AT THE SAME SPEED, MEANS FOR 